The present invention generally relates to an electromagnetic switching device, for example a contactor. Preferably, it relates to one having a switching device enclosure and having a detachable unit which can be inserted into the switching device enclosure at an insertion point. More preferably:
the detachable unit holds a magnet yoke to which a coil unit is fitted, by which a pull-in force can be exerted on an armature,
two fastening attachments are included, which respectively point forward and to the rear seen in the insertion direction, being integrally formed on the magnet yoke.
A switching device is known, for example, from WO 95/12891. In this document, the fastening attachments have through-holes, in which latching hooks engage which are integrally formed on the detachable unit.
Further electromagnetic switching devices having a switching device enclosure and having a detachable unit which can be inserted into the switching device enclosure are known, for example, from DE 29 01 552 C2 and from DE 32 20 040 C2.
DE 26 20 210 A1 discloses an electromagnetic switching device in which an E-shaped magnet yoke has fastening attachments, which point outward and can be inserted into attachment receptacles in the switching device enclosure, on its outer limbs. A similar disclosure content can be found in DE 42 36 900 A1.
The detachable units according to the prior art are all relatively complicated, with a comparatively large number of parts. They thus have a relatively high magnet movement tolerance.
An object of an embodiment of the present invention is to provide an electromagnetic switching device having a switching device enclosure and having a detachable unit which can be inserted into the switching device enclosure. Preferably, the switching device and/or the detachable unit have a simpler design but nevertheless operates reliably, while the magnet movement tolerance of the magnet system remains small.
An object may be achieved in that a holding bracket, which extends transversely with respect to the insertion direction, may engage over one of the fastening attachments in order to hold the magnet yoke. Further, it may engage under two holding tongues, which are integrally formed on the detachable unit.
In comparison to WO 95/12891, this results in the magnet yoke being held better and in a simpler fashion, while in comparison to DE 29 01 552 C2 and DE 32 20 040 C2, it results in a considerable saving in individual parts.
If the switching device enclosure has a holding bracket contour on which the holding bracket is supportedxe2x80x94directly or via the holding tonguesxe2x80x94when the detachable unit is inserted, the holding tongues have to be able to withstand only the natural weight of the magnet yoke, but not forces which occur during operation of the switching device.
If the holding tongues are elastically connected to the detachable unit, this results in the magnet yoke being fastened in a particularly simple and reliable manner.
The other fastening attachment can in principle likewise be connected to the detachable unit via a holding bracket and holding tongues. However, a physically simpler design is achieved if the other fastening attachment is inserted into an attachment receptacle. The attachment receptacle is in this case preferably integrally formed on the detachable unit. If the attachment receptacle is arranged in front of the holding bracket, seen in the insertion direction, this results in the detachable unit design being physically even simpler.
If the attachment receptacle is designed to be elastic in height, this results in the magnet yoke being held in a clamped manner. If the switching device enclosure has a receptacle contour on which the attachment receptacle is supported when the detachable unit is inserted, the attachment receptacle also has to be able to withstand only the natural weight of the magnet yoke.
If the attachment receptacle and the receptacle contour first of all interact via an insertion incline during insertion of the detachable unit, this allows the detachable unit to be inserted into the switching device enclosure without any snagging and without being subject to tolerances.
If a latching hook for latching the detachable unit in the switching device enclosure and an operating element for the latching hook are integrally formed in a sprung manner on the detachable unit, no separate latching hook is required for latching. A bar spring preferably engages over the latching hook and/or the operating element in order to provide force assistance.
If the coil unit has a coil and a contact foot which is connected to the coil via an intermediate structure, rests on a foot contact on the detachable unit at the side underneath the coil and is at a distance from the coil, this results in the coil unit being supported robustly, in a simple manner.
If the foot contact is arranged recessed in the detachable unit, such that the contact foot is recessed in the detachable unit, this results in the detachable unit having a small physical height. If the switching device enclosure has a coil contour on which the coil unit is supported when the detachable unit is inserted, there is no need for the operating forces to be absorbed by the detachable unit. The coil unit can be supported on the coil contour via the contact foot, for example.
If the coil unit is braced by the coil contour and the detachable unit, the coil is fixed in the switching device enclosure without any play. It can thus not oscillate freely.
If the coil unit has a switch which can be operated by the armature via an operating element, the operating element is mounted in a bearing which is arranged on the coil unit and the switching device enclosure has positioning and supporting elements, by which the bearing can be positioned during insertion of the detachable unit and is supported when the detachable unit is inserted, the operating element can be aligned exactly with respect to the armature in a simple manner.
If the switching device enclosure has a recess on a side opposite the insertion point, via which recess the detachable unit can be driven out of the switching device enclosure by means of a driving-out tool, the detachable unit can be disconnected from the switching device even in the event of a defect in a comparatively simple manner, namely in particular without complete disassembly of the switching device.